|
%I #11 May 02 2014 03:57:47
%S 312211322212221121123222114,13112221133211322112211213322114,
%T 312211322212221121123222115,13112221133211322112211213322115,
%U 312211322212221121123222116,13112221133211322112211213322116,312211322212221121123222117,13112221133211322112211213322117
%N Isotopes of Conway's audioactive transuranic elements, in reversed lexicographic order.
%C The transuranic elements Pu=31221132221222112112322211 and Np=1311222113321132211221121332211 are alternating prefixes;
%C n is suffix of a(2*n - 1) and of a(2*n) in decimal representation.
%H Reinhard Zumkeller, <a href="/A215403/b215403.txt">Table of n, a(n) for n = 1..500</a>
%H J. H. Conway, <a href="http://dx.doi.org/10.1007/978-1-4612-4808-8_53">The weird and wonderful chemistry of audioactive decay</a>, in T. M. Cover and Gopinath, eds., Open Problems in Communication and Computation, Springer, NY 1987, pp. 173-188.
%H Kevin Watkins, <a href="http://www.cs.cmu.edu/~kw/pubs/conway.pdf">Abstract Interpretation Using Laziness: Proving Conway's Lost Cosmological Theorem, </a>
%H Kevin Watkins, <a href="http://www.cs.cmu.edu/~kw/pubs/conwayslides.pdf">Proving Conway's Lost Cosmological Theorem, POP seminar talk, CMU, Dec 2006</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/LookandSaySequence.html">Look and Say Sequence</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Look-and-say_sequence">Look-and-say sequence</a>
%o (Haskell)
%o a215403 n k = a215403_list !! (n-1)
%o a215403_list = map (foldr (\d v -> 10 * v + d) 0) $
%o concatMap (\x -> map (x :) [plut', nept']) [4..] where
%o plut' = [1,1,2,2,2,3,2,1,1,2,1,1,2,2,2,1,2,2,2,3,1,1,2,2,1,3]
%o nept' = [1,1,2,2,3,3,1,2,1,1,2,2,1,1,2,2,3,1,1,2,3,3,1,1,2,2,2,1,1,3,1]
%Y Cf. A119566, A213979.
%K nonn,base
%O 1,1
%A _Reinhard Zumkeller_, Aug 09 2012
|
